This renewal application seeks continuing support for the Microenvironmental Influences in Cancer Training Program (MICTP) at Vanderbilt University. Over the past 24 years and continuing with the 5-year period preceding this competitive renewal, we have been remarkably successful in recruiting and training excellent students and postdoctoral fellows, particularly those from groups underrepresented in science. Overall, the MIC training program encompasses a group of 26 faculty members from both the Vanderbilt University School of Medicine and the Meharry Medical College. The training program is conducted within a vibrant academic environment and is supported by close interactions with the Vanderbilt-lngram Comprehensive Cancer Center, the Vanderbilt Department of Cancer Biology, and the Vanderbilt-Meharry Alliance Program. In addition to departmental and preceptor-specific laboratory instruction, each trainee receives cancer-related training in the form of two courses focused on cancer biology, a grant workshop, an annual Tumor-Host Interaction Program retreat, and a Clinical Experience. Trainees within the program are actively mentored by both faculty members and through paired peer mentoring by former student and postdoctoral trainees. Furthermore, predoctoral students are supported by an Interdisciplinary Graduate Program and an independent graduate program in Cancer Biology. Postdoctoral trainees are supported by an institutional Office of Postdoctoral Affairs, which provides both financial and academic support as well as career development advice and opportunities. Significant institutional investment in training programs, core facilities, state-of the-art laboratories and equipment further enhances trainee development. Training in this critical area of cancer research is necessary to build the workforce required to understand the complexities of the microenvironmental influence on cancer development and progression, and to translate this information into more effective and less toxic approaches to the treatment and prevention of cancer. Furthermore, training in tumor microenvironment will prepare our students and postdoctoral fellows to solve the major unsolved or neglected problems, the provocative questions, in oncology.